Martial Arts generally improves reaction time more than pure speed, which is a trait of athleticism/youth. It's why older Martial Artists move after their opponents but hit first.
Feng qingyang said that at his age, he wouldn't try to outspeed his faster opponents, but instead would out think them, which is perfect for using DG9J in a sublime way (compared to Linghu Chong's spectacular but 'clumsier' executions)